It Won't Render: Stuck on the 1st 4 tiles, played with Resolution, sample size and max steps with no luck
Your screenshot indicates that you are using square samples. This means that for 500 square samples, this becomes 250,000! 

This will consume quite a bit of resources, and very likely take quite some time. Unless you really want to render with that many samples, I would uncheck square samples, or change this to something more reasonable (like 45-55
). If this is your final render, perhaps 2000-3000 (not squared) may be sufficient.